Process for making gasoline



R. c. HOLMES T AL.

PROCESS FOR MAKING GASOLINE Original Filed Nov. 21 191 W I-1F! Ill l Tii ii: g l \HHHIIHIII anvemtozs Patented May 1 8, 1926.

UNITED STATES" A ENT- oF-FIcE.

ALPH c. HOLMES, or NEW YORK, N. Y., rRRnERIeK T. MANLRY, or nonstick AnnOTTOBEHIMER, or PoRT ARTHUR,

TEXAS, ASSIGNORS To T ETExAs courmy',

or NEW YORK, N. Y., A ooRroRATIoN or TEXAS.

rRooEss roR Magma GASOLINE.

" Original application filed-November 21, 191s,seria1m. 263,562. Divided1923, Serial No. 630,242. Divided and this application filed August 18,1925.. Serial 116. 49,962.

This inventionv relates-to methods of making condensable light oils,such as gasoline.

More particularly 1t relates to certaln novel improvements in thecracking of -hydro-'- carbons whereby higher boiling hydrocarbons aredecomposed into those "of lower boiling: point.

- This application is a division of our copending application, Serial-630,242, filed April 6,1923, which itself is a division of ourcopending' application, Serial 263,562, filed November 21,1918.

.In rior methods of cracking hydrocarbbn' oils, considerable difiicultyhas been e X-. perienced on account ofcarbon formations, which occuronthe sides of tubes and stills exposed to the heat required to carry onthe cracking operation.

It is a broad novel feature of the ,he-rein disclosed process thatsubstantially all of the cracking operation occurs in a vessel to whichno external heat is applied, except-at suchtimes and in such quantitiesas are necessary to compensate for heat losses, the oil prior to itsintroduction to such vessel having been subjected to a high degree ofcrack ing heat and the excess heat of the oil itself being used toeffect its own decomposition. As a consequence, we avoid substantialcarbon formation of the destructive character whichhave' proved such animpediment to prior systems. The removal of the cracking operation fromthe heating zone also reduces the danger from fires such as frequentlyoccur where cracking is carried on in highly heated stills and coilsexposed -to direct heat.

More specially our process preferably embodies a novel cyclic system inwhich a circuit of oil is constantly maintained under varying liquid andvapor phases. The oil to be treated on entering this circuit issubjected to a high degree of heat butt-he time element is so controlledwith respect thereto that there is comparatively little decompositionanddeposition of carbon while it is exposed to this external heat, theoil being rapidly removed from the heating zone and conducted to thecracking zone, where without necessarily being subjected to additionalheat, it undergoes a moleculardecomposition whereby carbon and lightproducts are formed and liberated. It will be' uiiderand applicationflled Apr1 1 a,

stood that oil cracking or conversion is dependent not only upontherelative conditions of pressure and temperature but also upon the timeelement with respect thereto,

; that is, the necessary pressure and temperature' must be. maintainedfor a sufficient period of time to enable the molecular decomposition orconversion to take place According to the present invention, this-timefactor is so controlled, by regulating the rate of heating the oilpassing through the heat- 1ng zone that the temperature thereof isprogressively raised in transit and reaches the desired crackingtemperature near the end of the heating coil at about the time ora'little before the oil emerges therefrom} Thus,

although the oil is subjected tocracking heats in the heating zone, thistemperature 1s attained only just previous to the exit of theoiltherefrom, and therefore, the oil leaves the heating coil before anysubstan tial decomposition and incident deposition of carbontakes place.'Subsequently, the highly heated oil in a state of incipientdecomposition, is delivered tothe cracking zone, where the desiredtemperature 'and pressure conditions are continuously sustamed and thecracking of the oiland the incident decomposition of carbon areeffected. The bulk of the carbon is removed from the circuit bywithdrawing from the crackmg zone. portions of the residual oil.Although the process, in its broad conception,

is complete atthis stage of the operation,

the light products preferably continue the cycle, leaving the crackingzone in the form of vapor and gas. are then subjected to a reduction 1ntemperature', whereby the heavier constituentsthereof, such as kerosene,are condensed- The condensate preferably 1s combined with the Thesevapors and gases charging oil entering the heating zone, thus completingthe cycle. The constituents of the desired volatility are removed fromthe circuit and condensed. The outlets from the circuit are socontrolled'that the entire system is maintained under ,a pressuresufiicient to insure the. desired molecular transformation.

Our process is to be distinguished from those of the prior art, in whicha circuit of liquid residuum is kept in circulation. hen such oil iskept in circulation, considerable quantities of carbon are formed,

owing to the readiness with which this type.

of oil carbonizes when exposed to high temperatures. the carbon formingin line particles in the oil. and wherever it cognes in contact with theheated metal surfaces,it attaches itself thereto and builds up deposits,which often cause the choking of tubes and coils. It also crystallizesthe metal surfaces, thereby decreasing the tensile strength of the metaland causing the bulging and breaking of such surfaces. Any residual oilresulting from the cracking operation will necessarily contain aconsiderable amount of heavy polymerization products and carbon held insuspension in the oil, and to circulate such a residue through heatedtubes is to continually pass into or produce in such tubes a largeamount of free carbon. In our system, we do not circulate a residuum,but instead keep the residual oil removed from the application ofexternal heat and ,withdraw the heavier portions thereof, which containthe bulk of the carbon, from the cycle at the cracking zone, andcontinue the cycle by means of the vapor generated, which contains thecondensable product desired and also certain heavier vaporousconstituents which are used to complete the cycle. By removing theheavier residuum from the cycle, we keep the circuit free from thissource of carbon formation, and since we conduct substantially all ofthe cracking in a vessel to which either no external heat is applied oronly a small quantity of heat is applied to maintain the requisitetempera.- ture conditions, we are thus able to effectively remove thecarbon formed.

In cracking oil for gasoline, there is generally formed a considerablequantity of vapors heavier than gasoline, which may be generallydesignated by the term, kerosene. \Ve preferably employ these heaviervapors as a carrier for the lighter vapors; they assist in maintaining acurrent of vapor by which the gasoline is removed from the cracking zoneto a separator where the kerosene vapors are condensed and removed fromthe gasoline vapors which pass on to the condenser. The kerosenecondensate, preferably at a temperature, not materially below itsboiling point, is injected or otherwise suitably forced into the heavyoil charge enterin; and flowing through the heating tubes whereby afoamy agitated mixture is produced by the acceleration of thecirculation in the heating tubes resulting from the increased volume ofoil therein, thereby preventing the settling and flow of the heavierportions of the oil along the bottom of the highly heated tubes and theconsequent local overheating and carbonization of the oil,

thus keeping the tubes substantially free from any slight carbonformations. These kerosene constituents are an excellent mechanicalconductor of heat, and there is thus produced a heat cycle whichmaterially assists in maintaining the proper temperatures in the heatingand cracking zones. By maintaining these bodies in constant circulation,the kerosene constituents, which under existing methods have been foundso dillicult to decompose into lighter products, are, in our system,ultimately reduced to gasoline.

"We have devised certain novel apparatus which is adapted for carryingout our process, and illustrates the preferred form thereof in thedrawings in which,

Figure l is a diagrammatic elevation of said apparatus;

Figure 2 is a detail view of a modified cracking drum which may besubstituted for that of Figure 1.

It will be understood that other apparatus besides that illustrated maybe used in carrying out our process.

Referring to Fig. 1 of the illustrative drawings, a tubular heating coil1 is located in a furnace 2, having a burner 3 and a stack 4. As shownfor illustrative purposes, the coil 1 comprises a plurality ofhorizontally disposed rows of tubes extending through the furnace andplaced the one above the other. The adjacent ends of each alternate pairof tubes in each horizontal row are conveniently connected together byhorizontally positioned return bends or fittings to form horizontalcoils. The several horizontal coils thus arranged are con venientlyconnected together at their righthand ends by vertically disposed returnbends or fittings, as shown in Fig. 1, to form a single elongated andcontinuous heating coil through which the oil flows and is heated to therequired degree. This coil is of extended length and restrictedcross-section and has a relatively large and effective heating surfacewhereby the stream of oil passing therethrough is enabled to etficientlyabsorb heat and reach a high temperature with rapidity. A checkeredbrick baflle 5 having openings (3 may serve to distribute the heatevenly over the coil. A fresh oil charging line 7, having a jet orinjector 7, extends to a pump 8, which is connected to a suitable sourceof oil supply (not shown). The pipe 9, having a valve 10, extends fromthe heating coil 1 to an enlarged cracking drum or chamber ll, Withinwhich it inayterminate in a distributor 9. This distributor 9 may be ofany suitable form to thoroughly distribute and diffuse the charging oilthrough out the body of oil in the drum whereby-an intimate contactofthe highly heated charging oil with the body of oil in the drum iseffected. The cracking drum is preferably provided with a jacket 11 ofsuitable in outlet 23.

sulating material to protect it against heat radiation and is equippedwith a valved draw-off 12, a vapor outlet 13, and an oil gauge 14. Thevapor outlet 13 extends to a separator 15, having a vapor outlet 16, anda condensate outlet 17. The vapor line 16 terminates in a water-cooledcondenser coil 18, having an outlet 19 equipped with aregulatablepressure valve 20. If desired the valve 20 may be placed inthe vapor line 16 but We prefer to maintain the pressure in the heatingcoil, cracking drum and separator through the condenser. The outlet 19terminates in a collecting tank 21, having a valved gas outlet 22 and avalved distillate The condensate line 17, which is preferably insulated,as indicated at 17 is equipped with a valve 17 and is connected to thecharging line 7 at the jet 7 In conducting the process with theapparatus illustrated, the oil to be treated is forced through thecharging line 7 under considerable pressure, and is rapidly flowedthrough the heating coil 1, where it is heated to the desired crackingtemperature. Preferably this temperature is somewhat higher than thetemperature at which it is desired to conduct the cracking operation andmay or may not result in substantial vaporization. The oil on beingforced through the coil acquires a high cracking temperature, but onaccount of the rapidity of its flow, decomposition is only in theincipient stages when the oil is discharged through the pipe 9 into theheat insulated cracking drum 11 where a constant body of oil ismaintained at a crackingtemperature under pressure. The distributor 9,if employed serves to discharge the oil into the cracking drum in a widestream, thus thoroughly mixing the hot oil with the liquid body of oilmaintained in the drum and diffusing the heat therethrough. This heatdili'usion is materially aided by using a distributor with serratededges. The rapid flow of the oil through the coil where it is closelyconfined is here suddenly retarded, as the oil enters the drum which isof ample volume. Thus the excess heat of the oil operates to maintainthe body of oil at the desired cracking temperature and moleculardecomposition and distillation are carried on vigorously, the higherboiling hydrocarbons continually breaking up into hydrocarbons of lowerboiling point. The vapors and gas generated gather in the upper part ofthe cracking drum and pass out through the'vapor outlet 13 to theseparator 15, where there is effected a separation of hydrocarbons ofdesired volatility from those of less volatil ity. The hydrocarbons ofthe desired volatility pass out through the vapor line 16, by which theyare conducted to the condenser 18, where they are condensed, and thecondensed distillate is either intermittently or preferably continuouslyallowed to run 1 into the collecting tank 21.

The temperature in the air condenser 15 is such that the less volatilehydrocarbons are condensed and dropped into the conduit 17, by whichthey are conducted while still hot to the jet in the charging line orother suitable device for forcing the condensate into the chargingstream. The separator is preferably somewhat elevated so'as to give aconsiderable head of liquid in the pipe 17, which preferably contains aU bend, as illustrated, in order to form a liquid seal therein. Thishead of liquid, together with the high pressure at which the oil in thecharging line passes the jet, this pressure being ordinarily from 50 to100 pounds higher than the pressure in the drum, insures that thecondensate shall be constantlyand positively drawn into the chargingline and forced into the coil 1. The introduction of this hot condensateinto the charging line increases the volume ofjoil in the heating coiland thereby accelerating the flow therein and producing a foamy mixtureso that local overheating is prevented and the coil is keptsubstantially free from any slight carbon formations. Thiscon 'densateconsists in a type ofhydrocarbon which when decomposed does not yieldany great amount of carbon so that the oil charge is constantly beingdiluted with oil capable of being decomposed into lighter productswithout the production of large amounts of carbon. This condensatereaches the jet in a heated condition, pref- .erably at a temperaturenot materially below its boiling point, so'as to heat the charge of oilentering the heating coil. The heat cycle formed by the keroseneconstituents contributes to the maintenance of the proper temperaturesin the heating coil and the cracking drum. By injecting or otherwisesuitably forcing this condensate into the heating coil weincrease thevolume of oil flowing therein without increasing the total amount of oilcharged into the system at any given time.

A considerable pressure is maintained throughout the system, whichpressure is regulated by means of the valve 20 or the valve on the gasoutlet 22. The pressure used varies with the character of the oiloperated on and the character of the product desired. Ordinarily thedecomposition in the cracking drum iscarried' on under a pressure offrom 100 to 400 pounds. In utilizing oils of the type, commonly employedfor decomposition into products of the nature of gasoline a temperaturein the drum 11 of from 700 F. to 850 with a temperature in the coil 1 offrom 700 F. to 950 F.- is ordinarily used. For example, in cracking aparafiin base gas oil of a Baum gravity of about 34, a temperature of850 F. in the coil and of 775 F. in the drum with a pressure ofapproximately 200 pounds has been used to advantage.

The oil to be decomposed is constantly forced into the heating coilthereby causing a steady stream of heated oil to enter the crackingchamber. The residuum is Withdrawn preferably at such a rate that thereis maintained a constant body of oil in the cracking zone.

It is desirable to equip the apparatus with the valves and 17 so that incase there is a break in the heating coil the effect of any fireresulting may be localized by closing said valves, whereby the bulk ofoil in the system will be retained in the cracking drum 11. It isunderstood that in the normal operation of the process these valves areopen.

Auxiliary heat may be supplied to the cracking drum in any suitablemanner if desired, and a convenient method of providing this auxiliaryheat is, as shown in Fig. 2, to insulate only the upper part of the drumand apply heat at a moderate temperature or in a relatively smallquantity from any suitable heater such as is designated 30. In the earlystages of a run, since there is no danger of overheating a carbon-freesurface, the drum may be heate'd freely until the necessary heat cyclehas been generated and decon'iposition has begun. For this reason thearrangement of Fig. 2 possesses certain advantages over that of Fig. 1.But when decomposition begins, with a consequent deposition of carbon,the heat must be reduced, as otherwise the carbon would accumulate onthe hot surfaces and build up tenacious formations thereon, thuspreventing the effectual removal of the carbon and asphaltic bodies. Asthe run continues only a moderate heat is applied, sufficient only tooifset the loss ofheat due to radiation and distillation. If desired thedrum may be heated by means of waste heat from the furnace 2 or in anyother suitable manner.

The product obtained by the herein disclosed process is, for acrackedproduct, remarkably sweet, in other words, low'in unsaturated compounds.

It is understood that we use the terms gasoline and kerosene in thisapplication by way of example and that these terms are taken as types ofother similar distillates which may be produced by our process. We usethe term gasoline as an example of the volatile product desired whichunder the temperatures and pressures used is a vapor in the separator 13and is condensable in the cooling coil 18. We use the term kerosene asan example of those constituents which under the temperatures andpressures used is a- Vapor in the vapor line 13 but is condcnsable inthe separator 15. It is to be messes noted that the gravity and boilingpoint of the products which will condense in the separator 15 dependsupon the temperature therein under the pressures used.

A though for illustrative purposes the invention has been shown anddescribed in connection with apparatus of more or less specific detailsof construction, arrangement and location of parts, and as embodying inits mode of operation a certain series and sequence of somewhat definitesteps and operating conditions, it will be understood that many of theobjects and advantages of the invention may be obtained, to a greater orless extent, through the employment of apparatus of modified characteror, in fact, through variations or, in some cases, omissions, of certainof the component steps, without departing from the spirit and scope ofthe invention.

hat we claim is:

1. The process of converting hydrocarbon oil which comprises forcingsaid oil through a coil and drum while applying heat to said coil anddrum and allowing the vapors generated to develop pressure untildecomposition of the hydrocarbon begins, then reducing the heat app iedto the drum while securing it against substantial loss of heat throughradiation and vaporization, and continuously supplying to the oil. inthe drum the necessary heat for decomposition by means of the stream ofoil entering from the coil, the stream entering the coil beingcontinuously comminglcd with a hot condensate separated out from thegenerated vapors.

2. The process of converting hydrocarbon oil which comprises forcingsald oil through a coil and drum while applying heat to said coil anddrum and allowing the vapors generated to deve op pressure untildecomposition of the ll \'(ll'()Clll'l)Oll begins, then reducing'theheat applied to the drum while securing it against substantial loss ofheat through radiation and vaporization, and continuously supplying tothe oil in the drum the necessary heat for decomposition by means of thestream of oil entering from the coil.

3. The process of converting hydrocarbon oil that comprises forcing astream of oil through an elongated passageway of restricted.cross-section and thence into an enlarged chamber while applying heatfreely to both said passageway and said chamber to rapidly raise the oilto a cracking temperature and deve op a superatmospheric cracking'iressure therein and, after said condil ions of ten'iperature andpressure have been attained, applying to said enlarged chamber reducedor moderate heat suflicient only to maintain a cracking temperature insaid chamber while continuing the free application of heat to saidpassageway.

oil'that comprises passing a stream of oil through an elongatedpassageway of restricted cross-section, and then dehvering it into anenlarged zone where a body of oil is maintained, freely heating the oilin said passageway and'in said'enlarged zone' during the starting perioduntil cracking conditions of temperature and pressure are established,and subsequently continuing the free heating of the 011 in saidpassageway but applying to the body of oil in said enlarged zoneareducedand moderate amount of heat sufiicient to offset heat losses andto maintain a. cracking temperature therein throughout the period ofnormal operation.

5. The process of converting hydrocarbon oil that comprises freelyheating a moving stream of oil in its passage through a heat- 20 ingcoil and distillation drum during the starting period to rapidlyestablish cracking conditions of temperature and pressure therein, thencontinuing the maintenance of .said conditions during the period ofnormal cracking operations by heating the oil in said drum at a reducedand moderate rate while continuing to freely heat the oil in the coil,removing the vapors from the distillation drum, and separating out andreturning to theheating coil the condensed heavier fractions thereof. 7

In witness whereof I have hereunto set my hand this 23rd day of July,1925.

RALPH C. HOLMES. In witness whereof I have hereunto set my hand this24th day of July, 1925.

FREDERICK T. MANLEY. In witness whereof I have hereunto set myhand this25th day of July, 1925.

' OTTO BEHIMER.

